Homobimetallic complexes of ligand having O- and S-donor sites with same and different di- and trialkyl/aryltin(IV) moiety: their synthesis, spectral characterization and biological activities

Homobimetallic complexes with oxygen and sulphur donor ligand have been synthesized at room temperature under stirring conditions using R₂SnCl₂ (R?=?Me, n-Bu) and R₃SnCl (R?=?Me, n-Bu, Ph) in 1:1 molar ratio. The synthesized complexes have been characterized by elemental analysis, IR and multinuclear NMR (¹H, ¹³C) spectroscopy. These complexes have also been screened for their biological activities. IR data show that the ligand acts in a bidentate manner and exhibits trigonal bipyramidal geometry in solid state which is also confirmed by semi-empirical study. NMR data show that reported complexes exhibit tetrahedral geometry in solution. Results of antimicrobial screening activities indicated that complexes (6) and (7) are very effective antibacterial and antifungal agents, respectively, and they might indeed be a potential source of antimicrobial agents, while the complex (3) exhibits significant free radical scavenging ability with lower IC₅₀ value of 99.47?±?1.2???g/mL. Results of cytotoxicity/haemolytic activity showed the significant value of % haemolysis for complex (7) (18.101?±?2.3), while complex (4) was found to be least cytotoxic (5.733?±?1.0). Only a few colonies are observed in mutagenicity testing by Ames test.     

In-situ photoelectron spectroscopy with online activity measurement for catalysis research

We report Ambient pressure X-ray Photoelectron Spectroscopy Endstation with an integrated chemical analytical system that consists of a residual gas analyzer in the 2nd differential pumping stage and a new low-reactive sample holder heating assembly. This system has a linear response to the reaction chamber gas pressure. The sample heating assembly also has a low dark reaction rate up to 400 °C for H₂ and CO oxidation. We expect this chemical analytical system will expand our capabilities in conducting in-operando catalysis research.     

Why are the Elemental Nonmetals (F2, Cl2, Br2, I2, S8, P4) of so Many Hues or of Any Hues and Where is the Chromophore? Insight into Intera-X–X Bonds

A unique approach is used to relate the HOMO-LUMO energy difference to the difference between the ionization potential (IP) and electron affinity (EA) to assist in deducing not only the colors, but also chromophores in elemental nonmetals. Our analysis focuses on compounds with lone pair electrons and σ electrons, namely X₂ (X = F, Cl, Br, I), S₈ and P₄. For the dihalogens, the [IP – EA] energies are found to be: F₂ (12.58 eV), Cl₂ (8.98 eV), Br₂ (7.90 eV), I₂ (6.78 eV). We suggest that the interahalogen X–X bond itself is the chromophore for these dihalogens, in which the light absorbed by the F₂, Cl₂, Br₂, I₂ leads to longer wavelengths in the visible by a π → σ* transition. Trace impurities are a likely case of cyclic S₈ which contains amounts of selenium leading to a yellow color, where the [IP – EA] energy of S₈ is found to be 7.02 eV. Elemental P₄ with an [IP – EA] energy of 9.09 eV contains a tetrahedral and σ aromatic structure. In future work, refinement of the analysis will be required for compounds with π electrons and σ electrons, such as polycyclic aromatic hydrocarbons (PAHs).     

Catalytic and Thermodynamic Characterization of Endoglucanase (CMCase) from <Emphasis Type="Italic">Aspergillus oryzae</Emphasis> cmc-1

Monomeric extracellular endoglucanase (25 kDa) of transgenic koji (Aspergillus oryzae cmc-1) produced under submerged growth condition (7.5 U mg⁻¹ protein) was purified to homogeneity level by ammonium sulfate precipitation and various column chromatography on fast protein liquid chromatography system. Activation energy for carboxymethylcellulose (CMC) hydrolysis was 3.32 kJ mol⁻¹ at optimum temperature (55 °C), and its temperature quotient (Q ₁₀) was 1.0. The enzyme was stable over a pH range of 4.1–5.3 and gave maximum activity at pH 4.4. V _max for CMC hydrolysis was 854 U mg⁻¹ protein and K _m was 20 mg CMC ml⁻¹. The turnover (k _cat) was 356 s⁻¹. The pK _a1 and pK _a2 of ionisable groups of active site controlling V _max were 3.9 and 6.25, respectively. Thermodynamic parameters for CMC hydrolysis were as follows: ΔH* = 0.59 kJ mol⁻¹, ΔG* = 64.57 kJ mol⁻¹ and ΔS* = −195.05 J mol⁻¹ K⁻¹, respectively. Activation energy for irreversible inactivation ‘E _a(d)’ of the endoglucanase was 378 kJ mol⁻¹, whereas enthalpy (ΔH*), Gibbs free energy (ΔG*) and entropy (ΔS*) of activation at 44 °C were 375.36 kJ mol⁻¹, 111.36 kJ mol⁻¹ and 833.06 J mol⁻¹ K⁻¹, respectively.     

Removal of metal ions using metal-flavonoid-DNA adduct protocol

An attempt has been made to incorporate intercalation power of metal-flavonoids (metal-Fls) into ds.DNA for selective accumulation of heavy metal ions on DNA trapping water insoluble (3-aminopropyl)triethoxysilane (APTES) films. Three flavonoids (Fls) namely primuletin (prim), morin (mor) and quercetin (quer) were used to chelate heavy metal ions alone and through calf thymus DNA intercalation. Metal ion (M?=?Cu²⁺, Fe³⁺, Cr³⁺, As²⁺, Hg²⁺, Pb²⁺, Cd²⁺, Sb⁵⁺) captured from 10?µM solution of its salt over Fl-DNA-APTES film was found to be more efficient towards metal ion removal (99% removal) than M-Fl interaction into DNA-APTES (80% removal) which in turn was better than M-Fl-DNA trapping into APTES (60% removal). M-Fl chelation was 1:1 for all the complexes and binding strength (K_b in M^?1) was of the order of 10³–10⁵ for different flavonoids (Fls) and the flavonoid-chelated metals (M-Fls). From the results, it was inferred that the nature of interaction between different constituents and metal chelation with the flavonoid are the key factors that affect the ion removal efficiency. It was also anticipated that any flavonoid can be used for ion removal process subject to its affinity strength towards the ion of interest. The work successfully demonstrated the usefulness of the method for ion removal in chemical, biological and environmental systems.     

Development and Optimization of Methylcellulose-Based Nanoemulgel Loaded with Nigella sativa Oil for Oral Health Management: Quadratic Model Approach

The present study aimed to develop a local dental nanoemulgel formulation of Nigella sativa oil (NSO) for the treatment of periodontal diseases. NSO purchased from a local market was characterized using a GC–MS technique. A nanoemulsion containing NSO was prepared and incorporated into a methylcellulose gel base to develop the nanoemulgel formulation. The developed formulation was optimized using a Box–Behnken statistical design (quadratic model) with 17 runs. The effects of independent factors, such as water, oil, and polymer concentrations, were studied on two dependent responses, pH and viscosity. The optimized formulation was further evaluated for droplet size, drug release, stability, and antimicrobial efficacy. The developed formulation had a pH of 7.37, viscosity of 2343 cp, and droplet size of 342 ± 36.6 nm. Sustained release of the drug from the gel for up to 8 h was observed, which followed Higuchi release kinetics with non-Fickian diffusion. The developed nanoemulgel formulation showed improved antimicrobial activity compared to the plain NSO. Given the increasing emergence of periodontal diseases and antimicrobial resistance, an effective formulation based on a natural antibacterial agent is warranted as a dental therapeutic agent.     

3-Methyl-2-(phenylsulfonamido)butanoic Acid and Its Metal Complexes: Synthesis,Crystal Structure,Antimicrobial, and Enzyme Inhibition Activity

Russian Journal of General Chemistry - In this study sulfonamide ligand, 3-methyl-2-(phenylsulfonamido)butanoic acid, has been synthesized and introduced in complexation with metals Cu, Zn, Fe, Ni,...     

Entropy generation in nanofluid flow of Walters-B fluid with homogeneous-heterogeneous reactions

Research on optimization of entropy generation in nanofluid flow gained much interest. In this study, the Walter's-B nanofluid flow is considered to analyze the irreversibility in cubic autocatalysis. Fluid motion is considered in presence of viscous dissipation, magnetohydrodynamics (MHD), radiation, and heat generation absorption. Homotopy analysis method (HAM) is employed to solve nonlinear ordinary differential system. Results show that fluid flow reduces for larger Weissenberg and Hartman numbers. Temperature gradually enhances for larger Weissenberg number and radiation parameter. For higher estimation of thermophoresis parameter, the temperature and concentration are enhanced. Opposite impact of Hartman and Weissenberg numbers is noticed for entropy generation and Bejan number. Disorderedness and Bejan number are reduced near the sheet, while the opposite trend is seen away from the sheet.     

Versatile nanocomposites in phosphoproteomics: A review

Protein phosphorylation is one of the most important post-translational modifications. Phosphorylated peptides are present in low abundance in blood serum but play a vital role in regulatory mechanisms and may serve as casual factors in diseases. The enrichment and analysis of phosphorylated peptides directly from human serum and mapping the phosphorylation sites is a challenging task. Versatile nanocomposites of different materials have been synthesized using simple but efficient methodologies for their enrichment. The nanocomposites include magnetic, coated, embedded as well as chemically derivatized materials. Different base materials such as polymers, carbon based and metal oxides are used. The comparison of nanocomposites with respective nanoparticles provides sufficient facts about their efficiency in terms of loading capacity and capture efficiency. The cost for preparing them is low and they hold great promise to be used as chromatographic materials for phosphopeptide enrichment. This review gives an overview of different nanocomposites in phosphoproteomics, discussing the improved efficiency than the individual counterparts and highlighting their significance in phosphopeptide enrichment.     

Thermal catalytic conversion of the used isobutyl isoprene rubber into valuable hydrocarbons

An environment friendly method, thermal catalytic pyrolysis of used isobutyl isoprene rubber was investigated. In this method, the used inner butyl tube rubbers were catalytically pyrolyzed into valuable hydrocarbons and carbon black. In this method, the tube rubber was pyrolyzed both thermally (with out catalyst) and catalytically in a batch reactor under atmospheric pressure. The effect of temperature, the amount of catalyst, and the reaction time on the yields of the pyrolyzed products were investigated. Char yield decreased with increase of pyrolysis temperature while total gas and liquid yields increased. The liquid fraction was obtained with boiling point up to 478 K. At optimum conditions, the liquid product was collected and analyzed for different fuel properties. Typical analysis of the used isobutyl isoprene rubber oil for both the cases of parent and refluxed oil has been performed. Phenols and carbonyls were quantitatively determined by spectrophotometric methods using folin-denis and phenyl hydrazine reagents, respectively. The distillation data showed that ~100% of oil has boiling point <473 K which is the boiling point for 80% of distilled product in commercial kerosene. Its specific gravity, viscosity, freezing point, Cetane number, and diesel index were also within the limits of kerosene.